title: Novel pentagonal silicon rings and nanowheels stabilized by flat pentacoordinate carbon(s).
abstract: It is predicted by accurate density functional and coupled-cluster theory that planar [Si(5)C](2-) and [Si(5)C](1-) rings can be stabilized by flat pentacoordinate carbon-silicon bonds. The energy difference of the [Si(5)C](2-) dianion from the lowest energy three-dimensional isomer is about 12.2 kcal∕mol at the level of the density functional theory using the Becke 3-parameter (exchange), Lee, Yang and Parr functional, and the triple-ζ doubly polarized basis sets. Stable composite [Si(5)C](2) structures are formed either as nanowheels with axial C-C bonds of 1.51 Å or as isoenergetic pentagonal graphiticlike layers with double C-C distance (3.02 Å) and almost double aromaticity index, based on nucleus independent chemical shifts. Both of these structures are at least 12 kcal∕mol lower in energy than the lowest energy Si(10)C(2) structure reported in the literature, but about 5 kcal∕mol higher than the lowest energy structure found here.
authors.affiliation: Department of Physics, University of Patras, GR-26500 Patras, Greece. zdetsis@upatras.gr
authors.forename: Aristides D
authors.initials: AD
authors.lastname: Zdetsis
mesh_terms: D002244:Carbon / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D011789:Quantum Theory; D012825:Silicon / Q000737:chemistry*
chemical_list: D002244:Carbon; D012825:Silicon